This invention relates to a holder for nautical charts designed to protect the charts from the elements -- wind, spray, and rain; and yet provide easy visual reference. Since the inception of this invention its primary contemplated use has been in the context of "open cockpit boats," but its application is not limited to boats in this category, as will be explained below. The term "open cockpit boat" as used herein means those craft generally included in the category of day sailors and those which have little or no protection against the weather other than perhaps a windshield or a light canvas top. Such craft are normally simply sailed or driven (i.e., controlled with respect to course and position by visual reference to land or navigational aids such as beacons and buoys), rather than navigated in the sense that one's course and position are determined by computations and the plotting of fixes upon charts. Consequently, the present invention is designed for use with piloting charts or those navigation charts which already have all necessary notations thereon. The present invention makes no provision for the making of navigation computations and/or notations directly on the face of the cover.
It is well known that the studying of a navigation chart of any kind in an open cockpit boat, or for that matter in any vessel wherein the helmsman is in an open or exposed position, while under way is difficult even under the best conditions, and that in foul weather it is next to impossible. Take for example the case of an open cockpit boat which after a day's run approaches an unfamiliar harbor at dusk in a light rain. The harbor channel is marked; however, in order to follow the markings correctly, frequent reference to a nautical chart is necessary. At this point a number of serious difficulties for the craft's operator, especially if he is alone, become clear. (1) The rain, the darkness, and the cumbersome size of such charts all tend to make accurate reading difficult, (2) The rain and spray tend to blur the chart and will eventually ruin it, (3) Nautical charts are usually merely paper and thus cannot be put down in order to free the operator's hands for other duties without the chance that a sudden gust of wind will result in the loss of the chart overboard with consequent danger to the craft and its passengers, and (4) Such charts lack the rigidity to be effectively usable except in a repeatedly folded single hand-holdable state.
Various means have been employed in an attempt to cope with the above problems. For example, plastic pouches, some secured to the craft and some not, have been used. Such pouches do protect the chart from weather and spray, and if secured to the craft also protect against loss. The problem with such a pouch however is its inconvenience. The chart must be removed for use and returned after each use for protection. In a complex piloting situation requiring frequent reference to the chart such a pouch would clearly not be used for its intended purpose, so the basic problems discussed above remain for these periods at least.
Another possible solution used by some sailors is to cut out and paste a section of chart on a piece of plywood and to coat the unit thus created with shellac to make it water repellant. At first blush this solution appears satisfactory. The chart is protected from the elements, portable and is of sufficient weight so as not to be blown overboard; moreover, the chart is displayed flat and the plywood board may be placed in any desired position, both of these being features which facilitate use.
This solution is fine as far as it goes, but it has no flexibility. The size of coast and geodetic charts varies, and in some cases may run as large as 351/2 inches .times. 471/2 inches. A board this large is clearly much too big for convenient use in an open cockpit boat. Experience indicates that a board of approximately 12 inches .times. 12 inches to 14 inches .times. 12 inches is the largest size conveniently usable in such craft. This in turn indicates that only approximately one quarter of a total chart may be practically mounted as above. Thus limited, this solution too is unsatisfactory. It is not uncommon for open cockpit boats to make runs along the coast of 70 miles or more for overnight stays, yet the solution indicated above is limited to 1/10 of a single chart area, typically only a few square miles.
It is therefore evident that either each chart carried must be cut and mounted as above (not to mention cataloged for reference), or the operator must put up with the above-recited problems, or a means must be devised providing a solution to the above problems while at the same time providing practical operational flexibility.